socket_accept

    (PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

    socket_accept — 接受套接字上的连接

    说明

    socket_accept(Socket $socket): Socket|false

    socket 是从 socket_create() 创建，使用 socket_bind() 绑定，socket_listen() 监听的一个套接字实例。此函数接受在 socket 上创建的连接。当连接被成功创建后，返回一个可用于通信的 Socket 实例。若有多个连接排队，返回队头第一个连接。若没有待处理的连接，那么 socket_accept() 默认阻塞，直到有一个连接出现。如果 socket 使用 socket_set_blocking() 或 socket_set_nonblock() 设置为非阻塞，那么 socket_accept() 将直接返回 false。

    socket_accept() 返回的 Socket 实例不能用于接受新的连接。但 socket 依然保持打开状态，并且可以继续接受新的连接。

    参数

    socket

    使用 socket_create() 创建的 Socket 实例。

    返回值

    成功时返回一个新的 Socket 实例，错误时返回 false。可以通过调用 socket_last_error() 来检索实际的错误代码。将错误代码作为参数传递给 socket_strerror() 以获得错误的文本解释。

    更新日志

    版本 说明
    8.0.0 成功时，该函数现在返回一个 Socket 实例；在此之前，返回值是一个 resource。

    参见

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    用户贡献的备注 5 notes

    up
    24
    lars at opdenkamp dot eu
    16 years ago
    If you want to make a daemon process that forks on each client connection, you'll find out that there's a bug in PHP. The child processes send SIGCHLD to their parent when they exit but the parent can't handle signals while it's waiting for socket_accept (blocking).

    Here is a piece of code that makes a non-blocking forking server.

    #!/usr/bin/php -q
    <?php
    /**
    * Listens for requests and forks on each connection
    */

    $__server_listening = true;

    error_reporting(E_ALL);
    set_time_limit(0);
    ob_implicit_flush();
    declare(    ticks = 1);

    become_daemon();

    /* nobody/nogroup, change to your host's uid/gid of the non-priv user */
    change_identity(65534, 65534);

    /* handle signals */
    pcntl_signal(SIGTERM, 'sig_handler');
    pcntl_signal(SIGINT, 'sig_handler');
    pcntl_signal(SIGCHLD, 'sig_handler');

    /* change this to your own host / port */
    server_loop("127.0.0.1", 1234);

    /**
    * Change the identity to a non-priv user
    */
    function change_identity( $uid, $gid )
    {
    if( !    posix_setgid( $gid ) )
    {
    print     "Unable to setgid to " . $gid . "!\n";
    exit;
    }

    if( !    posix_setuid( $uid ) )
    {
    print     "Unable to setuid to " . $uid . "!\n";
    exit;
    }
    }

    /**
    * Creates a server socket and listens for incoming client connections
    * @param string $address The address to listen on
    * @param int $port The port to listen on
    */
    function server_loop($address, $port)
    {
    GLOBAL     $__server_listening;

    if((    $sock = socket_create(AF_INET, SOCK_STREAM, 0)) < 0)
    {
    echo     "failed to create socket: ".socket_strerror($sock)."\n";
    exit();
    }

    if((    $ret = socket_bind($sock, $address, $port)) < 0)
    {
    echo     "failed to bind socket: ".socket_strerror($ret)."\n";
    exit();
    }

    if( (     $ret = socket_listen( $sock, 0 ) ) < 0 )
    {
    echo     "failed to listen to socket: ".socket_strerror($ret)."\n";
    exit();
    }

    socket_set_nonblock($sock);

    echo     "waiting for clients to connect\n";

    while (    $__server_listening)
    {
    $connection = @socket_accept($sock);
    if (    $connection === false)
    {
    usleep(100);
    }elseif (    $connection > 0)
    {
    handle_client($sock, $connection);
    }else
    {
    echo     "error: ".socket_strerror($connection);
    die;
    }
    }
    }

    /**
    * Signal handler
    */
    function sig_handler($sig)
    {
    switch(    $sig)
    {
    case     SIGTERM:
    case     SIGINT:
    exit();
    break;

    case     SIGCHLD:
    pcntl_waitpid(-1, $status);
    break;
    }
    }

    /**
    * Handle a new client connection
    */
    function handle_client($ssock, $csock)
    {
    GLOBAL     $__server_listening;

    $pid = pcntl_fork();

    if (    $pid == -1)
    {
    /* fork failed */
    echo "fork failure!\n";
    die;
    }elseif (    $pid == 0)
    {
    /* child process */
    $__server_listening = false;
    socket_close($ssock);
    interact($csock);
    socket_close($csock);
    }else
    {
    socket_close($csock);
    }
    }

    function     interact($socket)
    {
    /* TALK TO YOUR CLIENT */
    }

    /**
    * Become a daemon by forking and closing the parent
    */
    function become_daemon()
    {
    $pid = pcntl_fork();

    if (    $pid == -1)
    {
    /* fork failed */
    echo "fork failure!\n";
    exit();
    }elseif (    $pid)
    {
    /* close the parent */
    exit();
    }else
    {
    /* child becomes our daemon */
    posix_setsid();
    chdir('/');
    umask(0);
    return     posix_getpid();

    }
    }

    ?>
    up
    18
    Boylett
    16 years ago
    If you want to have multiple clients on a server you will have to use non blocking.

    <?php

    $clients     = array();
    $socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
    socket_bind($socket,'127.0.0.1',$port);
    socket_listen($socket);
    socket_set_nonblock($socket);

    while(    true)
    {
    if((    $newc = socket_accept($socket)) !== false)
    {
    echo     "Client $newc has connected\n";
    $clients[] = $newc;
    }
    }

    ?>
    up
    4
    Greg MacLellan
    20 years ago
    The socket returned by this resource will be non-blocking, regardless of what the listening socket is set to. This is actually true for all FCNTL modifiers.
    up
    2
    renmengyang567 at gmail dot com
    5 years ago
    <explain>
    This case is a very simple interaction between the TCP client side and the TCP server side

    <?php
    // create for simple-tcp-server
    $sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
    socket_bind($sock, '127.0.0.1',5000);
    socket_listen($sock,1);
    $clnt_sock = socket_accept($sock); //阻塞
    $st = "hello world ^_^";
    socket_write($clnt_sock, $st,strlen($st));
    socket_close($clnt_sock);
    socket_close($sock);
    ?>

    <?php
    //create for simple-tcp-client
    $clnt_sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
    socket_connect($clnt_sock, '127.0.0.1', 5000);
    $ret= socket_read($clnt_sock, 1024);
    print     "from simple-tcp-server:".$ret.PHP_EOL;
    socket_close($clnt_sock);
    ?>

    <fruit>
    from simple-tcp-server:hello world ^_^
    up
    -1
    gmkarl at gmail dot com
    17 years ago
    Be aware signal handler functions set with pcntl_signal are not called while a socket is blocking waiting for a connection; the signal is absorbed silently and the handler called when a connection is made.
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